<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        form{
            width: 550px;
            height: 550px;
            margin: 50px auto;
            border: 2px solid white;
            position: relative;
        }
        div{
            width: 550px;
            height: 550px;
            background-color: black;
            opacity: 0.3;
            position: absolute;
            top: 0px;
            left: 0px;
            display: none;
            color: white;
            font-size: 50px;
            text-align: center;
            line-height: 550px;
        }
        form:hover div{
            display: block;
            border-color: blue;
        }
    </style>
</head>
<body>
    <form action=""method="">
        <input type="text" placeholder="账号:">
        <input type="submit"value="按此提交"><br>
        <input type="password"placeholder="请输入密码："><br>
          <input type="text"list="one">
        <datalist id="one">
            <option value="例如：">csy12994489</option>
            <option value="例如：">baaall_kllls@</option>
        </datalist><br>
        <select name="yanse" id="yanse">
            <option>红色</option>
            <option>绿色</option>
            <option>白色</option>
        </select><br>
        <label for="three">/*用label做扩大选择域，即是点字就可以选上*/
        <input type="checkbox"id="three">男
        </label>
        <label for="four">
        <input type="checkbox"id="four">女
        </label><br>
        <input type="radio">吃
        <input type="radio">不吃
        <br>
        <div>神秘表格</div>
    </form>
</body>
</html>